Polycationic Ligands in Gold Catalysis: Synthesis and Applications of Extremely π-Acidic Catalysts
作者:Javier Carreras、Gopinadhanpillai Gopakumar、Liangu Gu、Ana Gimeno、Pawel Linowski、Jekaterina Petuškova、Walter Thiel、Manuel Alcarazo
DOI:10.1021/ja411146x
日期:2013.12.18
Very often ligands are anionic or neutral species. Cationic ones are rare, and, when used, the positively charged groups are normally appended to the periphery of the ligand. Here, we describe a dicationic phosphine with no spacer between the phosphorus atom and the two positively charged groups. This structural feature makes its donor ability poorer than that of phosphites and only comparable to extremely
配体通常是阴离子或中性物质。阳离子基团很少见,使用时,带正电的基团通常附加到配体的外围。在这里,我们描述了一种在磷原子和两个带正电荷的基团之间没有间隔基的双阳离子膦。这种结构特征使其供体能力比亚磷酸盐差,只能与剧毒或自燃化合物如 PF3 或 P(CF3)3 相媲美。通过利用这些特性,开发了一种新的 Au 催化剂,显示出显着增强的激活 π 系统的能力。这已被用于合成空间位阻非常大且天然存在的 4,5-二取代菲。本方法有望适用于许多其他过渡金属催化转化的开发和改进,这些转化受益于极强的 π 受体配体。已通过密度泛函计算探索了选定催化转化的机制。